The invention relates to cleaning installations for tube bundles such as those equipping condensers of large steam turbines, heat exchangers of nuclear reactors . . . , such installations employing the forced flow in these tubes of balls of elastic material whose diameter is slightly greater than the diameter of the tubes, said flow being imposed by the liquid circulated through said tubes, and for example, being constituted by water drawn from a river.
It relates more particularily, among said installations, to those which comprise, between the outlet and the inlet of the tube bundle, a recycling system for balls comprising essentially a grid extending across the outlet pipe of said bundle so as to recover the balls emerging from this bundle, and a recycling pipe system or piping adapted to receive a flow of the abovesaid liquid charged with balls so recovered and to reinject this flow into the inlet pipe of the tube bundle, said pipe system passing successively through a drive pump and a ball collector, said collector being particularily constituted by a receptacle which can be isolated and opened.
To remove worn balls from said installations, that is to say balls whose diameter has become insufficient to ensure effective cleaning of the tubes, it has been proposed to include in these installations a separating or sorting chamber bounded by a screen, located inside the ball collector and joined to a point, of the recycling pipe system, situated downstream of this collector, the pipe which joins said chamber to said point passing through a basket for gathering and removing worn balls collected in the chamber.
The screen was then sheet metal perforated by circular openings having a diameter substantially equal to that of the worn balls to be removed and hence less than that of the sound balls.
Because of the elastic nature of the constituent material of the balls, those having a diameter slightly greater than that of the worn balls to be removed had a tendency to penetrate in part into the openings of the screen and to become jammed in these openings, with the risk of rapidly clogging the screen and of thus rendering it inoperative.
Attempts have been made to overcome this serious drawback by creating turbulence in the carrier liquid of the balls just upstream of the screen. However, in practice, the drawback indicated has not been really overcome.
It is a particular object of the invention to overcome this drawback.